The present invention relates generally to a prosthetic limb, and more particularly to methods and to apparatus for fabricating a cosmetic cover for a prosthetic limb.
A prosthetic limb is used to replace an amputated portion of a limb and to help restore the amputee""s ability to use the limb. A prosthetic leg for a lower extremity typically will include artificial foot and ankle components coupled to an upright assembly which, in turn, is coupled to a custom-fitted socket assembly. If the amputation is above the knee, the upright assembly typically includes an artificial knee joint. Often, a cosmetic cover is fabricated to cover the prosthetic limb, such as to cover a prosthetic leg from the socket downward to the artificial foot.
In one conventional method for fabricating a cosmetic cover for a prosthetic leg, the artificial foot is first removed. Then, a cosmetic cover blank is obtained having the shape of a tapered cylinder with a constant wall thickness. The cosmetic cover blank is made of a foam material such as PVC (polyvinyl chloride) foam, EVS foam, ethafoam, or polyethylene foam. The cosmetic cover blank is heated to expand to a point where it will slide over the prosthetic limb. It is noted that differing diameters cause the proximal end of the cosmetic cover blank (i.e., the end of the cosmetic cover blank designed to be closest to the residual limb) to expand more than the distal end of the cosmetic cover blank (i.e., the end of the cosmetic cover blank designed to be farthest from the residual limb). Then, the heated and expanded cosmetic cover blank is slid onto the prosthetic leg. The socket has a bonding agent to bond the inside surface of the cosmetic cover blank to the outside surface of the socket, and a vacuum is applied to draw the cover onto the prosthetic leg as it cools. After cooling, the artificial foot is reattached, and the distal surface of the cosmetic cover blank is bonded to the proximal surface of the artificial foot. The cosmetic cover blank is then manually xe2x80x9cshavedxe2x80x9d to mimic the anatomy of a sound limb using at least the dimensions of the circumference of the ankle and calf section of the amputee""s sound leg. A spray skin finish or cosmetic hose is then applied to the covered prosthetic leg. This method is labor intensive.
In another conventional method for fabricating the cosmetic cover for a prosthetic leg, disclosed in U.S. Pat. No. 5,880,964, a computer-aided-design (CAD) system with a digitizing tool is linked to a computer-numerically-controlled (CNC) milling machine. A cosmetic cover blank, or a longitudinal half blank (i.e., a blank cut in two along its longitudinal axis), is obtained. The prosthetic leg is fitted to the wearer""s residual leg and is adjusted. The digitizing tool takes measurements of the prosthetic leg, such measurements being used by the CAD system to command the CNC milling machine to carve the inside surface of the cosmetic cover blank. The digitizing tool also takes measurements of the amputee""s sound leg, such measurements being used by the CAD system to create a mirror-image leg to command the CNC milling machine to carve the outside surface of the cosmetic cover blank. The carved cosmetic cover blank is then attached to the prosthetic leg. This method requires a new form of cosmetic cover blank that is not presently on the market.
What is needed is a method for fabricating a cosmetic cover for a prosthetic limb which is not labor intensive and which does not introduce unwanted tolerances between the finished cosmetic cover and the prosthetic limb.
A first method of the invention is for fabricating a cosmetic cover for a prosthetic limb. The prosthetic limb has a socket for placement over a wearer""s residual limb and has a component disposed exterior of the socket. The component and the distal end of the socket have alignable holes for attachment of the component to the socket. The method includes several steps. A cosmetic cover blank is attached over the prosthetic limb. A mandrel is obtained having a mandrel shaft and having a mandrel plate which is attached to one end of the mandrel shaft and which has holes matching the holes of the socket. The mandrel plate is positioned inside the socket. The holes of the mandrel plate, the socket, and the component are aligned. The mandrel plate, the socket, and the component are attached together through the holes of the mandrel plate, the socket, and the component. The mandrel shaft is placed in a chuck of a milling machine. Finally, the outside surface of the cosmetic cover blank is milled by the milling machine. Preferably, the mandrel shaft is placed in a chuck of a computer-numerically-controlled milling machine. The method for attaching the cosmetic cover blank to the prosthetic limb may include the steps of heating the cosmetic cover blank to expand it and then sliding the cosmetic cover blank over the prosthetic limb.
A second method of the invention is for fabricating a cosmetic cover of a prosthetic limb. The prosthetic limb has a socket for placement over a wearer""s residual limb, has a component located exterior of the socket, and has a lock located interior of the socket. The component and the distal end of the socket have aligned holes, wherein the holes of the component are threaded holes and wherein the lock has threaded bolts. The threaded bolts are rotatable from inside the socket, extend through the holes of the socket, and are engaged with the threaded holes of the component. The method includes several steps. A cosmetic cover blank is attached over the prosthetic limb. A mandrel is obtained having a mandrel shaft and having a mandrel plate which is attached to one end of the shaft and which has holes matching the holes of the socket. The lock is removed from the component and the socket. The removed lock is replaced with the mandrel plate and threaded fasteners which pass through the holes of the mandrel plate and the socket and which engage the threaded holes of the component. The mandrel shaft is placed in a chuck of a milling machine. The outside surface of the cosmetic cover blank is then milled by the milling machine. Preferably, the mandrel shaft is placed in a chuck of a computer-numerically-controlled milling machine.
A first expression of a preferred embodiment of the mandrel of the invention is for supporting, in a milling machine, a cosmetic cover blank attached to a prosthetic limb during milling of an outside surface of the cosmetic cover blank, wherein the prosthetic limb has a socket for placement over a wearer""s residual limb and has a component located exterior of the socket and wherein the component and the distal end of the socket have alignable holes for attachment of the component to the socket. The mandrel includes a mandrel shaft and a mandrel plate. The mandrel shaft has a first end for placement in a chuck of the milling machine and has a second threaded end. The mandrel plate has a threaded hole for engagement with the second threaded end of the mandrel shaft and has holes matching the holes of the socket. The mandrel plate is attachable to the component from within the socket through the holes of the mandrel plate, the socket, and the component.
A second expression of a preferred embodiment of the mandrel of the invention is for supporting, in a milling machine, a cosmetic cover blank attached to a prosthetic limb during milling of an outside surface of the cosmetic cover blank, wherein the prosthetic limb has a socket for placement over a wearer""s residual limb, has a component located exterior of the socket, and has a lock located interior of the socket. The component and the distal end of the socket have alignable holes, and the holes of the component are threaded holes. The lock has threaded bolts which are rotatable from inside the socket, which are positionable to extend through the holes of the socket, and which are engageable with the threaded holes of the component for attachment of the component to the socket. The mandrel includes a mandrel shaft and a mandrel plate. The mandrel shaft has a first end for placement in a chuck of the milling machine and has a second threaded end. The mandrel plate has a threaded hole for engagement with the second threaded end of the mandrel shaft and has holes matching the holes of the socket. The mandrel plate is attachable to the component from within the socket through the holes of the mandrel plate and the socket and the threaded holes of the component. Preferably, the method for attaching the cosmetic cover blank to the prosthetic limb first includes the sequential steps of fitting the prosthetic limb to the wearer""s residual limb, adjusting the prosthetic limb, and removing the prosthetic limb from the wearer""s residual limb.
Several benefits and advantages are derived from the invention. In the methods and expressions of a preferred embodiment of the invention, the cosmetic cover blank is attached to the fitted and adjusted prosthetic limb before shaping the outside surface of the cosmetic cover blank. This utilizes some of the same steps (except the carving step) as those conventional methods which heat a cosmetic cover blank, then slide the cosmetic cover blank over the prosthetic limb, and then manually carve the outside surface of the cosmetic cover blank. In the methods and expressions of a preferred embodiment of the invention, the mandrel allows the outside surface of the cosmetic cover blank to be milled by a milling machine while the cosmetic cover blank is attached to the prosthetic limb. This eliminates intensive labor steps compared to those conventional methods which require manually carving of the outside surface of the cosmetic cover blank.